The Hanford B Reactor outside Richland, Wash., became a National Historic Landmark in August 2008.

Standing alone, hulking and windowless, in southeastern Washington's desert, the Hanford B Reactor has been called "the atomic fortress that time forgot." But new tours take visitors inside this formerly top secret site where history was made.

Housing the world's first full-scale nuclear reactor, the complex produced plutonium for the first atomic blast—the Trinity test in New Mexico—and for Fat Man, the atom bomb dropped on Nagasaki, Japan, on August 9, 1945. Shut down in 1968 as part of the massive and ongoing cleanup of the 586-square-mile Hanford Site outside Richland, Wash., it became a National Historic Landmark last August.

"It's as if time froze inside the reactor buildings," says Portland architect Tim Cowan, who worked on preserving the site. "The original equipment with all of its dials, gauges, and switches is still there, looking like the set of a 1940s movie."

Radioactive contaminants have been removed or isolated. On free tours offered several days a week, visitors see the control room, the work area where fuel was loaded into the reactor core, and a small office used by Enrico Fermi, the Italian-born physicist who supervised the design. Displays, videos, and volunteer docents—many of them former Hanford employees—provide background. Visit www.hanford.gov[3] for details.

Photography courtesy U.S. Department of Energy

This article was first published in May 2009. Some facts may have aged gracelessly. Please call ahead to verify information.